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Ship Strikes: collisions between whales and vessels

Most reports of collisions between whales and vessels involve large whales, but all species can be affected.  Collisions with large vessels often go unnoticed and unreported. Animals can be injured or killed and vessels can sustain damage.  Serious and even fatal injuries to passengers have occurred involving hydrofoil ferries, whalewatching vessels and recreational craft.

The IWC and ship strikes

Both the Conservation and Scientific Committees of the IWC are working to understand and reduce the threat posed by ship strikes.  A Strategic Plan to Mitigate the Impacts of Ship Strikes has been developed and aims, by 2020, to develop approaches and solutions to  achieve a permanent reduction in ship strikes.  The IWC is also collaborating with other relevant organisations at both regional and inter-governmental levels to share information and expertise.  

Click here to read the IWC Strategic Plan to Mitigate the Impacts of Ship Strikes on Cetacean Populations, 2017-20.

Quantifying the problem

Evidence of ship strikes comes from a range of sources including direct reports from the vessel involved and examination of dead whales found floating at sea or washed up on the beach. In some cases, whales become lodged on the bulbous bows of large vessels and the crew may only become aware of this when the ship enters port. For every incident that is observed and reported there will be many others that are completely unseen.  This makes assessing the conservation implications of ship strikes very difficult.

For some populations, such as the North Atlantic right whale whose main habitat is the busy waters off the east coast of the USA and Canada, the mortality rate is particularly high compared to the overall population size. It is thought that mortality due to ship strikes may make the difference between extinction and survival for this species, and a range of mitigation measures have been developed. There are also concerns about the high collision rates for the population of fin whales in the Mediterranean. Reported ship strike numbers will never give accurate estimates of the numbers of whales involved and so there is a need for estimates based on an understanding of risk and relating this to densities of ships and whales.

The IWC Global Ship Strikes Database

In 2007, the IWC launched an initiative to collect and analyse information about reported ship strikes, both historic and current and on a global scale.  The aim of this work is to identify 'hot spots' where large numbers of whales coincide with busy shipping lanes.  Once this information was been checked and analysed, it will be shared with the widest possible range of stakeholders to help develop mitigation actions that are targeted and effective.   

If you have information relating to a collision between any type of vessel and a whale, dolphin or porpoise please click here to enter your information.

Mitigation Measures

There is no universal solution to the problem of ship strikes.  Technological, operational and educational solutions are all currently being explored and here you can read a summary of the different types of measure that have been implemented around the world.  For now, the most effective way to reduce collision risk is to keep whales and ships apart, and where this is not possible, for vessels to slow down and keep a look out.  All mitigation work needs to be undertaken in a collaborative way as migratory animals like whales travel across national boundaries.

The IWC is working in conjunction with other organisations such as the International Maritime Organization (IMO) and have produced an information leaflet with further advice to reduce the risk of collision. You can read this advice here.  The leaflet is also available in Arabic, Chinese, French, Russian and Spanish).